Electronic devices, for example in the form of control units of a motor vehicle, which include a relay, the relay including a coil which may be connected to a power source through a controllable switch, for example a transistor, and may thus be switched between an operating voltage potential and a reference potential. In motor vehicles and in other applications of the electronic device, voltage fluctuations may occur in the voltage supply of the power source, which may limit or interrupt the operation of the electronic device. To maintain acceptable operation of the electronic device, blocking capacitors are used for example, which may in addition include step-up switching regulators connected upstream from them. In addition a d.c. transformer is discussed in U. Tietze and Ch. Schenk, “Halbleiterschaltungstechnik” (“Semiconductor Circuit Engineering”), ninth edition, Springer-Verlag, Berlin, pp. 561 ff., in which a d.c. output voltage is set using a low-pass filter, which produces a mean time value. The magnitude of the output voltage may be specified by the pulse duty factor of a power switch of the voltage transformer.